Biology 1001A Study Guide - Midterm Guide: Genotype Frequency, Macrophage, Chromosomal Crossover
30 Apr 2012
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The two inside tails are hydrophobic, and the outside head is hydrophilic. They help make up the lipid bilayer, and control what substances leave and enter the cell. The lipid bilayer affects the fluidity of the membrane, and movement of the membrane. Lower temperatures cause the bilayer to be packed tightly, and this restricts the movement. Higher temperatures cause the bilayer to be more fluid, so the movement of the membrane increases. Fatty acids are non-polar and insoluble in water. Saturated fatty acids (animal fats) have no double bonds and no kinks, and they also tend to be solid at room temperature because they can bond together quite well. A higher concentration of saturated fatty acids in membranes cause the membrane to be less fluid, and this causes the melting point of the membrane to increase. Types of molecules that can freely cross membranes: small and hydrophobic molecules such as o2, h2o, co2.
